Heat, Corrosion & Chemical Resistant, Tantalum Is Unique Among Refractory Metals

Heat, Corrosion & Chemical Resistant, Tantalum Is Unique Among Refractory Metals

Tantalum Properties

Tantalum (pronounced tan-ta-lum) is number 73 on the periodic table. Rarely occurring in nature, tantalum is typically found in the ore columbite-tantalite. When refined, pure tantalum metal is a lustrous blue-gray color, similar in color to platinum.

Pure Tantalum: Tantalum has one of the highest melting and boiling points of all the chemical elements [3017 °C (5462 °F) and 5458 °C (9856 °F), respectively]. Its density (16.7 g/cm3), is nearly half again as high as lead’s (11.3 g/cm3). Its thermal conductivity [35 W/(M・K)] is quite low, only 20%-25% of molybdenum’s or tungsten’s, and less than half of iron’s. Its thermal expansion coefficient (6.3・10-6 K-1) is about 30%-40% higher than tungsten’s and 50% greater than molybdenum’s. Pure tantalum is a very ductile metal, and can be manipulated by bending, stamping & pressing.

Nickel Tantalum Alloys: When added as an alloy to nickel, the resulting alloys containing 3 – 11% tantalum exhibit enhanced strength, a higher melting point and are resistant to corrosion by hot gases.

Tantalum Alloys: When alloyed with other metals, tantalum is used to make super alloys used in chemical processing, jet engines and nuclear reactors. 

Aliquot Mold

Tantalum Applications

For applications that require increased heat, corrosion, and chemical resistance, tantalum is often the metal of choice. Tantalum offers one unique advantage over  all other metals – it forms an extremely stable oxide. This property is key to many tantalum applications, making it the metal of choice for many demanding applications;

Medical – Tantalum is frequently used in medical applications. Thanks to its oxide coating, tantalum is inert to bodily fluids and is highly biocompatible. Its high density makes it an efficient X-ray absorber, so tantalum stents and implants are easier for surgeons to image and monitor using X-rays during implantation. Traditional stent materials like Nitinol are coated with nanostructured tantalum to improve their X-ray visibility, enhancing stent manipulation and placement. Devices such as hip and knee joints, skull plates, suture clips, and mesh used to repair bone can all be made from tantalum.

Tantalum filaments used in Medical Application

Chemical Processing Equipment – Thanks to the properties of its oxide, tantalum is perhaps the metal most highly resistant to attack by both oxidizing and reducing acids, making it ideal for handling aggressive chemicals. Tantalum is often used in chemical processing equipment where hot, highly corrosive environments are encountered. Tantalum tubing is used for heat exchangers in a wide variety of chemical plants. In addition, large pressure vessels can be loosely clad with tantalum, or bonded to a cladding layer using controlled explosions to create an intimate, pore-free interface between the structural material and tantalum. Tantalum is also used in valves that regulate the flow of process chemicals, as rupture discs, and in dip probes that sparge vessel contents. Tantalum screws, bolts, and fixtures provide nearly unlimited service life in these applications.

Electronics Industry – Tantalum plays an important role in solid-state device manufacture and operation. It is estimated that upwards of 70% of electronic devices contain tantalum in one form or another.

Using tantalum allows engineers to create smaller & more efficient capacitors. High-Capacitance, High-Reliability Capacitors produced from tantalum are made from loosely sintered, electrically interconnected metal powder particles having a tantalum oxide coating. The oxide is the capacitor’s dielectric material, the interconnected powder particles are its anode, and a conductive medium infiltrated into the pore structure and connected to an external terminal is its cathode. The extremely small particles have a large surface area, which creates a large-area dielectric layer and allows a much larger amount of charge to be stored per unit volume of capacitor than in traditional designs that use metal foil.

As flat-panel displays grew larger and larger, their thin-film aluminum conductors could not transmit signals fast enough, leading to display performance problems. Copper conductors could easily solve the problem, but the silicon devices had to be protected from contamination by copper diffusion during high-temperature processing. A tantalum thin film under the copper conductors solved the problem since the thin film stopped copper diffusion into the silicon device and the tantalum did not diffuse into either the silicon or copper. Today, device manufacturers require tantalum sputtering targets specially processed to maximize thin-film uniformity.

Tantalum thin films also are an important part of ink-jet printer heads, where high elastic modulus and resistance to corrosion make tantalum the material of choice for printer-head ink chambers.

Tantalum parts used in electronics industry
Large flat panel displays – tantalum thin films make them possible

Military and Aerospace – Nickel/tantalum alloys are used extensively in military and commercial aircraft gas turbine engines where exposure to extremely high temperatures & stresses necessitate their use. The addition of tantalum to nickel superalloys helps improve their high temperature strength. As a result, the components made from these superalloys can operate at higher internal combustion temperatures and produce enhanced thrust efficiencies while lowering fuel consumption.

Forms of tantalum and examples of their most common uses;

  • Sheet/Plate – common uses include linings for vessels, vacuum furnace parts & heat exchangers. Sheet is also used as anti-corrosion cladding.
  • Rod/Wire – Thanks to its biocompatibility, tantalum wire is widely used in the production of prosthetic implants and other medical devices. In addition, tantalum wire is also used as heating elements in vacuum furnaces and chemical processing equipment.
  • Powder – In powder form, tantalum is used to produce electrical circuits, capacitors, and resistors.
  • Tubing –tantalum tubing is often employed in the chemical, petrochemical, and pharmaceutical industries for the processing of compounds that may weaken or destroy other metals. Columns, stacks, and piping are just some of the products constructed from tantalum tubing in these industries.
  • Foil (thin sheet) & Strips – Foil is used as liners in vacuum furnaces and other heat insulation applications. In addition, thin tantalum strips are deep drawn or formed by similar methods to produce crucibles, cups, and other laboratory equipment that requires an inert metal.
  • Machined & Fabricated Parts – Tantalum fabrications created from rod, sheet & plate can be found in high temperature furnace components, chemical processing equipment, cathodic protection systems for steel structures, corrosion resistant screws, nuts & bolts, prosthetic devices for humans, jet engine turbines (discs, blades, vanes), & rocket nozzles.

Tantalum – Industry Specifications

Pure Tantalum Specifications (ASTM)

  • Tantalum Rod & Wire – ASTM B365
  • Tantalum Tubing – ASTM B521
  • Tantalum Sheet, Plate, Strip & Foil – ASTM B708
  • Medical Grade Tantalum – ASTM F560

Tantalum, Pure & Alloy Specifications (UNS Codes)

  • Unalloyed Tantalum (EB Melted) – R005200
  • Unalloyed Tantalum (Powder Metallurgy Grade) – R05400
  • Tantalum 2.5% Tungsten – R05252
  • Tantalum 10% Tungsten – R05255
  • Tantalum 7.5% Tungsten – Spring Grade
  • Grain Stabilized – Furnace Grain

ASTM Tantalum Purity (Commercial Grades)

  • 99.5% Pure 3N5
  • 99.9% Pure 4N
  • 99.995% Pure 4N5
  • 99.999% Pure 5N

About Rembar Co. LLC

In business since 1950, Rembar is one of the USA’s largest stocking distributors of tantalum rod, wire, plate, sheet, foil & tubing. In addition, we precision-machine, form & fabricate tantalum parts of all sizes, shapes & complexities. With some of the shortest lead-times in the industry, Rembar excels in providing customers with top-quality mill products & fabricated parts fast!

From Concept to Prototype to Production, Rembar is uniquely qualified to assist you with your tantalum requirement. Whether you need small-quantity prototypes or mass production, we can help.

Call us today at (914) 693-2620 and speak with one of our knowledgeable sales engineers or visit our website at www.Rembar.com and use our “Fast Quote” form to submit your request.